Electricity - Current, Charges and Definitions

Question 1

Explain the structure of an atom at the sum-atomic level.

Answer 1

At the atomic level, and atom consists of 3 sub-atomic particles

Protons (positive charge)
Electrons (negative charge)
Neutrons (neutral charge)

Question 2

What is the Bohr Model?

Answer 2

The Bohr model is a 2D model which states the structure of the atom as we know it today. It was established post the plum-pudding model.

Question 3

Define charge. State its symbol and SI unit

Answer 3

Charge refers to the property of electrons or protons to repel or attract.

Symbol - Q
SI Unit - Coulombs (C)

1C is a huge number = 10^19 electrons

Question 4

Define current. State its formula, symbol and SI unit.

Answer 4

Current refers to the number of charges moving through a point in a circuit per unit time.

Symbol - I
Formula - I = Q/t (charge/time)
Unit - Amperes (A)

Question 5

Define voltage. State its formula, symbol and SI unit.

Answer 5

Voltage refers to the energy carried per 1 coulomb of charge

Symbol - V
Formula - V = E/Q (energy by charge) OR V = IR (Current x resistance. ~ Ohm’s Law)
Unit - Volts (V)

**Unit of energy is joules

Question 6

How does current relate to the movement of positive and negative charges?

Answer 6

The direction of current is same to the direction of moving positive charges and opposite to the direction of moving negative charges.

Question 7

What is a conductor?

Answer 7

A conductor is a material that allows charge (usually electrons) to flow through it easily because it has free moving electrons.

Question 8

What is an insulator?

Answer 8

An insulator is a material that does not allow the flow of charge through through it very easily because it does not have free electrons.

Question 9

How do we measure current?

Answer 9

1. Current is measured using an Ammeter
2. This ammeter must be connect in series
3. this ammeter must also have a very low resistance as it should not change the amount of energy taken from the circuit.

Question 10

Describe conventional current and electron flow.

Answer 10

1. Convention current flow - moves from the positive to negative terminal of the cell
2. Conventional electron flow - moves from the negative to the positive terminal of the cell
3. Positive charges do not move - it’s relative, conventional current